O2-branded Galaxy S II's get ICS update, unlocked UK models left waiting

Owners of O2-branded Samsung Galaxy S II phones should now be able to update to the latest version of Android, the network has announced. Writing on its official Twitter feed, O2 says the update to Android 4.0 Ice Cream Sandwich for its Galaxy S II users is now available through Samsung's Kies software. O2 is the second British network to release the update, joining Three, which launched its ICS build last week. T-Mobile UK and Orange are promising the update in April, while Vodafone says it's still testing its version.
However, in a bizarre (and frustrating) turn of events, unlocked Galaxy S II owners in the UK have been left waiting for their update. After informing customers that ICS for unbranded UK phones would be landing last Monday, March 19, Samsung now says it's not able to offer any estimated release date. In a post on its UK Facebook page, the manufacturer assures increasingly impatient users that it's going as fast as it can --

Samsung UK is working hard to bring Android 4.0 (Ice Cream Sandwich) to our Galaxy S II customers. We are unable to confirm exact dates as the software testing and approval process is subject to several variables, but we are working as quickly as we can. Thank you for your patience.

This development is a reversal of the usual Android update situation. Generally, when a new version is released, unlocked phones are the first to get it, while carrier-branded phones have to wait around a month for additional testing to be carried out. We're not sure exactly what's holding up the ICS release for unbranded British devices, as the update has already landed in many other countries, including Poland, Hungary, Sweden, and Korea.
Impatient Galaxy S II owners can always change their CSC code and apply another region's ICS update directly through the ODIN utility. Or for those feeling brave, there's also the option to root and install an ICS ROM directly through a custom recovery. (If you don't know what any of that means, you're probably better off sticking it out on Gingerbread until Samsung releases the official update package.)
As ever, Galaxy S II phones in the U.S. have a little longer to wait for their updates, on account of the hardware differences from carrier to carrier. Leaked builds for certain devices have started to appear over the past few days, though, which is a good sign.
Galaxy S II users, be sure to shout out in the comments and let us know if you've received your ICS update yet.